The underlying basis for cystic fibrosis will be sought for by assessing the properties of membrane glycoprotein metabolism in fibroblasts from normals and patients with cystic fibrosis. The incorporation of sugars and amino acids into complex proteins of the cell membrane will be examined. Cell membranes will be isolated and the turnover of membranes measured. Characteristics of membrane transport function will be examined with regard to cellular uptake of free sugars and amino acids.